Improvement in electro-harmonic telegraphs



E. GRAY.

ELEcfrno-HARMONIC TELEGRAPH.

Patented Jan. 1e. 1677,

' INVENTUR By .ttorney "UNITED STATES ELISHA GRAY, OF CHICAGO,`ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, i

PATnnnQnmcn TO THE HARMONIC TELEGRAPH COMPANY, OF NEW YORK CITY.

IMPROVEMENT INl ELECTRO-HARMONIC TELEGRPHS.

Specification forming part of Letters Patent No. 186,340, dated January 16, 1877; application led January 27, 1876. i

To all whom it may concern:

Be it known that l, ELIsHA GRAY, of Chicago, in the county of Cook and'State ot' Illi` sundry Letters Patent of the United States,

in which composite musical tones are transmitted through a single Wire, and analyzedfor' separated at the receiving end of theline by vibrating reeds, bars, or strings, tuned correspondently with the respective transmitters of the composite tones.

In-an application for Letters Patent of the United States filed by me February 23,1875, for transmitting musical vibrations by electricity, 1 have shown not only the variousdevices for transmitting or receivingthe musical impressions; but also one method of arranging the electric circuit for producing the desired result, including the relation of the main battery to` the line and instruments aty both ends, and described the effects produced.

In my prior patents and application aboveu entioned, the full force of the battery was at all times exerted upon the-line-that is to say, when one transmitter was employed, and the others were at rest, it worked with the full force of the whole main battery, and when all the transmitters were employed, the same force was necessarily dividedamong them; consequently the amplitude ofthe vibrations of any given tone would diminish orincrease, according to the number of tones simultanel ously sent to line, thus rendering analysis at' r the receiving end of the line more difficult.

- My present improvement contemplates the avoidance of this. objection, `by insuring the transmission of tones of uniform amplitude of wave, whether a greater or less number` of tones be transmitted simultaneously, which end l attain by combining each transmitter with its respectivesection of the main battery, by a short or shunt circuit, in "such mannerl that each section is utilized for the transmission ot' the vibrations for its own tone, without interfering or drawing upon theother `section ot'` the battery` or opening the main circuit. and when not transmitting, the unemployed sections of the battery flow steadily to line, Without affecting the working transmitters of the other sections.

My improvement thus possesses two dis tinguishing characteristics: first, that of a main circuit always closed; and, second, the passage through this circuit of a smooth current, so to speak, when all the transmitters arequiescent, each transmitter when in operation throwing its respective portion of said current into vibration, so t'nattheremay be a smooth current, and one or more vibratory waves simultaneously transmitted through the circuit, or the entire current may be thrown into vibration.

. The subject-matter claimed hereinafter will specifically be designated.

The accompanying drawings represent a perspective diagram ofso much of my im'- proveri apparatus as is necessary to illustrate the subject-matter claimed.V

UI have shown this apparatus as Vconstructed in thev best way now known to me; but it is yobvious that the details of construction of its various parts may be varied within certain limits,in-Ways well known to skillful electricians? l halve shown three transmitters with their batteries, and correspondingreceivers at each end` ot' the line, so arranged as to transmit three" messages each way simultaneously; but a greater or less number of transmitters and receivers may be employed, and theymight be so arranged as all to transmit one way instead of in opposite directions.`

It is deemed unnecessary to describe in detail here the construction of the battery,

`as it forms nopart ofthe subjectmatter claimed, and any of the well-known batteries of' the present day will work effectively with my improved apparatus. K

The construction of the transmitters and receivers is fully set forth and described in my Letters Patent and application abovementioned, and needs no reiteration here.`

Each battery is connected with its respective transmitter by a short circuit or shunt wire. Starting with battery No. l, G is the ground-wire connected atthe plus pole of the battery, which battery is connected up in the ordinary way and runs to lille at the other or minus(-)end, through the analyzing-re-l ceivers F E.' D. The lineV connects atthe other end through the analyzing-receivers C B A to the plus (-1-) pole of battery No. 2, and passes through inthe'ordinary way to the ground-Wire G at the minus pole ot' said battery.

The' circuit, thus far, is similar to kan ordinary Morse circuit closed, and without a key or other means of making or breaking the circuit.

A B G DE F represent' six sets of transmitters, each set being composed of a common open circuit, Morse telegraphic key, and a' musical-tone transmitter, such, for instance, as that described in Letters Patent No. 165,728, granted to me July 20, 1875, for im.- provement in transmitters for electro-har'- monic telegraphs. These transmitters are all alike in construction, but each one is tuned to a different pitch, and has a receiver, Al B C D E F', correspondently tuned, at the other end of the line.

nach battery is divided into sections 1 2 s,

4 5 6, not by separating or disconnecting its cells, but by throwinga short circuit or'shunt wire around each section. For instance, the trst'short circuit of battery l consists ot' the wires a b, the second of the wires b c, and the thirdof the wires c c', and so on. The number of cells in each section is determinedby the distance the tone is to be transmitted.

Each shunt-wire runs through its ownikey and vibrating transmitter. For instance, in section l ot' battery l, which is at the line end of the battery, a wire, a, passes from the minus pole of the battery to one bindingscrew of the transmitter A, at which point the circuit divides, one branch connecting to line L, and the other to. the vibrating bar ot' the transmitter through the break point, which is in this instance a shunting-point. The circuit then passes to the other bindingscrew, and thence to the key-lever.

The anvil or lower point of the key is connected directly with the ends of the wire b, which forms the dividing-line between sections l and 2, forming part of the short circuit ot' each section, and so on. Now, if the reed or bar ot' transmitter A be vibrated by its local battery, (which is omitted from the drawing t0 avoid complication, but the operation ot' which is well understood,) and the key belonging to it and in the same circuit with it be depressed, the shunt-circuit around section l will be completed every time the vibrating bar or reed makes contact with itsbreak-point, thus producing a set of waves or electrical vibrations throughout the line, the

'transmitter in operation.

waves-.succeeding each other at. the .rate per second corresponding to the vibrations of the transmitting reed or bar, which waves will induce corresponding impulses in all the magnets of a power approximating one-sixth of ythe whole battery.

Although these magnetic impulses are inducedl'in all the magnets in the circuit, one only will make an audible response, except to a very delicate test, .which one, in this instance, will be'the receiver marked A', as one whose reed or ribbon (or reed and box, the case may be) is tuned correspondently to the All the other sections-'of the apparatus are connected up and operated in a manner precisely similar, each operating on its own section of battery. Each transmitter differs in pitch from every other one, and has its complement in its corresponding receiver.

It will be observed that by working with this improved system the main circuit is never opened, owing to which fact the integ` rity of each set of waves is preserved intact, thus rendering analysis easy at the receiving end of the line.

The' utility of" the `device has beeny amply demonstrated by practical operation.

I claim as of my own inventionl. The improvement in the art of telegraphically transmitting composite tones, hereinbefore sett'orth, which consists in-working a closed circuit with a continuous current from a main battery, portions ot' the whole of which current are thrown into vibration at will by the transmitters.

2. The improvement-in theart of telegraphically transmitting and analyzing composite tones, hereinbefore set forth, which consists .in working a closed circuit with a continuous .current from a main battery, portions of the whole of which current are thrown into vibration at willl by the transmitters, each set of vibrations being audibly reproduced by a corresponding receiver.

3. rlhe combination, substantially as hereinbefore set forth, oi' a series of transmitters,

each operated by a local battery, a main battery, an'electric circuit, through which acontinuous current ows from saidl battery, and `shunt or short circuits between the main bat- 

